public static function BytestringToGUID($Bytestring) {
    $GUIDstring  = str_pad(dechex(ord($Bytestring[3])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[2])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[1])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[0])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= '-';
    $GUIDstring .= str_pad(dechex(ord($Bytestring[5])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[4])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= '-';
    $GUIDstring .= str_pad(dechex(ord($Bytestring[7])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[6])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= '-';
    $GUIDstring .= str_pad(dechex(ord($Bytestring[8])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[9])),  2, '0', STR_PAD_LEFT);
    $GUIDstring .= '-';
    $GUIDstring .= str_pad(dechex(ord($Bytestring[10])), 2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[11])), 2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[12])), 2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[13])), 2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[14])), 2, '0', STR_PAD_LEFT);
    $GUIDstring .= str_pad(dechex(ord($Bytestring[15])), 2, '0', STR_PAD_LEFT);

    return strtoupper($GUIDstring);
  }